Noncorrosive separator materials for electric double layer capacitor

The paper evaluates noncorrosive and inexpensive materials, namely polypropylene sheet, fiberglass, and glass wool, as potential separator materials for electric double-layer capacitor (EDLC) application. Using these materials as separators and the same activated carbon electrodes, properties of two-electrode capacitors filled with aqueous sulfuric acid (H₂SO₄) were investigated by cyclic voltammetry (CV) as well as galvanostatic and electrochemical impedance spectroscopy (EIS) measurements. Performance comparison of the tested capacitors with an identical capacitor with conventional cellulose separator was also carried out. As a benchmark, the noncorrosive-separator-based capacitors demonstrate comparable power and energy densities to those of a cellulose separator, with the highest specific capacitance of 131 F/g and lowest equivalent series resistance of 13 Ω for the glass wool separator. Application of such noncorrosive separators may realize the utilization of high-concentration aqueous electrolytes, leading to higher rating EDLCs at lower cost compared to organic-solution-based capacitors.